1. Field of the Invention
This invention relates to a method of renovating and/or protecting sewers and pipes. The invention is particularly suitable for, but not limited to, man-entry, circular and oviform sewers.
2. Prior Art
International Publication No. WO88/05884 (International Application No. PCT/AU88/00027) (Danby Pty Ltd) described a method for renovating and/or protecting sewers or pipes. A liner was formed from lengths of PVC panels cut to length and placed around the wall of the pipe, butt-jointed by joining strips. Each panel had a formation along one side complementary with a formation along the other side so that adjacent panels could be clipped together to form a liner extending from manhole to manhole along the sewer or pipe.
While this method was an improvement over existing methods, it had a number of practical limitations. Each panel had to be individually cut to length, positioned, engaged with the adjacent panel(s) and butt-jointed. As each panel was, eg. 200 mm wide, this was laborious. In addition, it was found that as further panels were positioned, their effective diameter would reduce and so the ends could not be easily butted together and the panels had to be hammered slowly around the wall to the desired diameter. It is believed that this "creep" or reduction in diameter resulted from the engagement of the side of a panel in the formation of the preceding panel. If the panels were cut progressively shorter to overcome the "creep" the ends could be butted together but the diameter of the resultant liner was reduced along its length.